Lysosomal enzymes contain 6-phosphomannosyl moieties which mediate their translocation to lysosomes. The lysosomal marker is synthesized by sequential action of UDP-N-acetyl glucosamine: lysosomal enzyme-N-acetylglucosamine-1-phosphotransferase and yield-N-acetylglucosaminyl phosphodiesterase. The proposed investigations are mainly centered on the studies related to these two particular enzymes which are involved in the synthesis of recognition marker. We plan to develop facile routes for the synthesis of a variety of suitable yield-D mannosyl saccharide derivatives required for the study of these two enzymes. Thus, our synthetic phosphodiester linked saccharides containing GlcNac yield 1 yield phosphoryl-6-Man yield 1 yield residue (or residues) will be employed for the substrate specificity of yield-GlcMAc-phosphodiesterase. These phosphodiester linked mannosyl saccharides can also be used as reference compounds when corresponding mannosyl saccharides (devoid of any phosphate group at C-6 position of mannose) are used as accepters for GlcNAc-l-phosphotransferase. For the latter enzyme various such yield-D-mannosyl saccharides will be also available in our laboratory. For the study of GlcNAc-l-phosphotransferase certain lysosomal enzymes will be made available. Some of these lysosomal enzymes, e.g. human hexosaminidase will be deglycosylated under mild conditions and linked to certain mannosyl saccharides of known structures for their further use for the study of transferase. Thus, we plan to develop specific and convenient assay procedures for the enzymes under investigation. Effect of other enzymes during the assay procedure of required enzyme will be carefully examined. Affinity chromatography will be used as one of the key steps for the purification of these enzymes. Appropriate ligands required for the enzymes will be prepared. Investigations for both of these enzymes have become extremely important, as these enzymes are likely to play a significant role in certain diseases related to lysosomal enzymes and genetic disorders.